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Privacy Fence

I have a retaining wall in my backyard that is 75' by 4'. I would like to find a plant that grows at least 10' tall for privacy. I was scared off by the bamboo, the 'clumping vs. running' and the upkeep. I would appreciate any suggestions that would fit my criteria but am primarily interested in 'tropical' type foliage. I am in Zone 9. Thank you.